feat(phase-c): resolve PhpMixed-conversion phase-b TODOs

Implement the foundational PhpMixed conversion infrastructure
(From<bool|i64|f64|String>, order-sensitive PartialEq matching PHP ===)
and resolve the category-G phase-b TODOs that depend on it:

- Fix VCS driver cache paths that discarded parsed JSON or diverged on
  null caches (svn/forgejo/gitlab/git-bitbucket/github).
- Wire up real conversions previously stubbed or dropped: suggests
  platform config, audit ignore-severities, composer_repository search
  and ProviderInfo, class_loader prefix/classmap merges, locker lock
  diff comparison, advisory JSON serialization, SPDX license fields.
- Make GenericRule take a typed ReasonData; populate RULE_ROOT_REQUIRE
  with the constraint and convert PhpMixed at the call sites.

1 files changed, 4 insertions, 3 deletions

diff --git a/crates/shirabe/src/repository/vcs/forgejo_driver.rs b/crates/shirabe/src/repository/vcs/forgejo_driver.rs
index 3c1366d..a40f6a9 100644
--- a/crates/shirabe/src/repository/vcs/forgejo_driver.rs
+++ b/crates/shirabe/src/repository/vcs/forgejo_driver.rs
@@ -347,9 +347,10 @@ impl ForgejoDriver {
         if !self.inner.info_cache.contains_key(identifier) {
             let composer = if self.inner.should_cache(identifier) {
                 if let Some(res) = self.inner.cache.as_mut().and_then(|c| c.read(identifier)) {
-                    // TODO(phase-b): JsonFile::parse_json returns PhpMixed; convert into Option<IndexMap>
-                    let _ = JsonFile::parse_json(Some(res.as_str()), None)?;
-                    None
+                    let parsed = JsonFile::parse_json(Some(res.as_str()), None)?;
+                    parsed
+                        .as_array()
+                        .map(|m| m.iter().map(|(k, v)| (k.clone(), (**v).clone())).collect())
                 } else {
                     let file_content = self.get_file_content("composer.json", identifier)?;
                     let c = VcsDriverBase::finish_base_composer_information(